1. Field of the Invention
The present application relates to a package structure and a fabrication method thereof. More particularly, the present application relates to a package structure integrating curing of an insulation paste and reflow of conductive bumps in a same heating process, and a fabrication method thereof.
2. Description of Related Art
Recently, with quick development of the integrated circuit (IC) technique and material technique, a size of a chip in the IC is gradually reduced, though a function thereof is increasingly improved, so that application of the IC technique is widespread. Therefore, products, such as handheld electronic devices, electronic dictionaries, digital cameras and various digital products, etc., manufactured according to the IC technique have a general trend of lightness, slimness, shortness and smallness.
The surface mounting technology (SMT) is a commonly used technique for mounting an electronic component or other components to a circuit board. According to the SMT, a size of a whole package structure can be reduced, which avails miniaturization of an electronic apparatus.
According to the known SMT, a reflow step is performed to conductive bumps between the electronic component and the circuit board after the electronic component is mounted to the circuit board, so that the conductive bumps may have a melted state or a semi-melted state to bond the electronic component and the circuit board. Then, an underfill is filled between the electronic component and the circuit board, and a curing step is performed to the underfill. Generally, a reflow temperature of the conductive bumps is required to be higher than a melting point of the conductive bumps, and a heating temperature for curing the underfill is far lower than the reflow temperature of the conductive bumps.
However, according to the known SMT, after the conductive bumps are reflowed, an underfill process is further performed, and steps thereof are quite complicated, which may influence a production yield. Moreover, since a fabrication condition of curing the underfill is different to a fabrication condition of reflowing the conductive bumps, two fabrication equipments have to be used, which may increase a production cost.
On the other hand, according to the known SMT, a method of forming the underfill is that after the electronic component is mounted to the circuit board, a dispensing step is performed outside a junction of the electronic component and the circuit board, so that the underfill can enter a space between the electronic component and the circuit board to wrap the conductive bumps according to a siphon phenomenon. Though, a part of the underfill is remained outside the electronic component according to such dispensing method, which may influence an appearance of the package structure.